From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 2264C6B0222 for ; Thu, 3 Jun 2010 10:28:40 -0400 (EDT) Date: Thu, 3 Jun 2010 16:27:17 +0200 From: Oleg Nesterov Subject: Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads Message-ID: <20100603142717.GC3548@redhat.com> References: <20100601212023.GA24917@redhat.com> <20100602223612.F52D.A69D9226@jp.fujitsu.com> <20100602213331.GA31949@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: KOSAKI Motohiro , LKML , linux-mm , Andrew Morton , KAMEZAWA Hiroyuki , Nick Piggin List-ID: On 06/02, David Rientjes wrote: > > On Wed, 2 Jun 2010, Oleg Nesterov wrote: > > > > This isn't a bugfix, it simply prevents a recall to the oom killer after > > > the kthread has called unuse_mm(). Please show where any side effects of > > > oom killing a kthread, which cannot exit, as a result of use_mm() causes a > > > problem _anywhere_. > > > > I already showed you the side effects, but you removed this part in your > > reply. > > > > From http://marc.info/?l=linux-kernel&m=127542732121077 > > > > It can't die but force_sig() does bad things which shouldn't be done > > with workqueue thread. Note that it removes SIG_IGN, sets > > SIGNAL_GROUP_EXIT, makes signal_pending/fatal_signal_pedning true, etc. > > > > A workqueue thread must not run with SIGNAL_GROUP_EXIT set, SIGKILL > > must be ignored, signal_pending() must not be true. > > > > This is bug. It is minor, agreed, currently use_mm() is only used by aio. > > It's a problem that would probably never happen in practice because No need to convince me this bug is minor. I repeated this every time. I only argued with the "isn't a bugfix, no side effects". > considered the ideal task to kill. If you think this is rc material, then > push it to Andrew and say that. No, I don't think it is strictly necessary to push this fix into rc. But I don't understand why this matters. And in any case, when it comes to oom, I am in no position to make any authoritative decisions. David, I don't understand why do you refuse to re-diff your changes on top of Kosaki's work. If nothing else, this will help to review your changes. Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org